The present invention broadly relates to the formation of multi-layer coils of substantially flat products and, more specifically, pertains to a new and improved method and apparatus for forming multi-layer coils from substantially flat, flexible products, especially printed products, arriving in imbricated product formation.
Generally speaking, the method of the present invention is one in which the flat products are wound-up together with a winding strap upon a winding mandrel with the winding strap lying on an outer side of the coil layer being formed.
The apparatus of the present invention comprises a drivably and rotatably journaled winding mandrel or core defining a winding drum, first conveyor means for conducting the flat products to a product coil forming on the winding mandrel and a winding strap or band capable of being connected with the winding mandrel and of being wound-up together with the flat products on an outer side of a coil layer being formed.
An apparatus of this type is known from the German Patent Publication No. 3,123,888, corresponding to U.S. Pat. No. 4,438,618, issued March 27, 1984, in which the printed products arriving in imbricated product formation are wound-up upon a winding mandrel or core together with a winding band or strap withdrawn from a supply roll and supporting from below the imbricated product formation to be wound-up. At the end of the winding procedure, the winding band or strap is wound around the completed coil or wound package one or more times such that each new layer of the winding band or strap overlies the previous layer of winding band or strap. The friction between the superposed layers of winding band or strap suffices to hold the wound product coil or package together.
It is well known that, for a given diameter of the product coil or wound package, the length of the wound-up imbricated product formation, and therefore the necessary length of winding band or strap, depends upon the thickness of the flat products. This means that in product coils or wound packages of constant diameter various lengths of winding band or strap are required. For this reason, in order to be able to form a product coil or package of the desired size in every case, the supply roll must always contain a sufficient amount of winding band or strap. It can therefore occur that, after completing a product coil or wound package, a remainder of winding band or strap remains upon the supply roll. In principle, various possibilities are available for handling this remainder.
For instance, the remaining length of winding band or strap can be wound around the completed product coil or wound package. However, this delays the completion of the product coil or wound package by a time interval dependent upon the length of the remaining winding band or strap. Furthermore, the coil diameter becomes greater by the amount of the additional layers of winding band or strap.
It is also possible to sever the winding band or strap after completion of the product coil or wound package and to leave the remainder of the winding band or strap on the supply roll. Such a procedure leads, however, to problems when the winding band or strap is to be reused for forming a new product coil after the flat products have been wound-off the winding mandrel. For the previously explained reasons it can occur that the winding band or strap previously shortened by severing the remainder is no longer sufficiently long for forming a new product coil which then requires a time-consuming splicing of winding band or strap segments.
It is further conceivable to leave the remainder of the winding band or strap on the supply roll and to transport and store the latter with the associated completed product coil or wound package. This is, however, a most inconvenient procedure in manipulation and also requires manual labor.
It has been proposed to avoid this disadvantage by mounting the winding mandrel and the supply roll for the winding band or strap in a common mobile frame in which both the winding mandrel and the supply roll permanently remain (cf. German Patent Publication No. 3,236,866, corresponding to the commonly assigned, copending U.S. patent application Ser. No. 06/432,557, filed Oct. 4, 1982, now U.S. Pat. No. 4,587,790, granted May 13, 1986). The winding band or strap is always connected with the winding mandrel, on the one hand, and with the supply roll, on the other hand, which means that any remaining winding band or strap present remains stored upon the supply roll. As long as a winding band or strap of a length sufficient for the greatest consumption of winding band or strap foreseen in service remains wound-up on the supply roll, product coils or wound packages formed from printed products of varying thicknesses can be produced with this known apparatus without difficulty. Nevertheless, a substantial construction outlay and a sufficiently great supply of winding band or strap, which in certain cases exceeds requirements, is necessary.
It is also known to arrange the supply roll for the winding band or strap within the interior of the winding mandrel and to unroll the length of winding band or strap required for the formation of the product coil or wound package from the supply roll and to wind it up upon a storage roll outside the winding mandrel before winding-up (cf. German Patent Publication No. 3,231,427 corresponding to the commonly assigned, copedding U.S. patent application Ser. No. 06/412,843, filed Aug. 30, 1982, now U.S. Pat. No. 4,532,750, granted Aug. 6, 1985). In this execution there is therefore always the proper length of winding band or strap available but, on the other hand, there is also a considerable construction outlay and the presence of a stored length of winding band or strap sufficiently great for all applications, i.e. the worse case, is necessary.